Did you wake up in a bit of a grumpy mood today for no reason?
You may not be the only one, as Monday 21 January is the gloomiest day of the year, according to experts.
They've used some complicated maths and have decided that Monday is the day when people are more unhappy than at any other time in the year.
It's all to do with Christmas having just finished, miserable weather, breaking New Year's Resolutions and not having much money to spend on things.
So are you feeling a bit sadder than normal, or are you still smiling?
Unfortunately this topic is now closed but there are Comments pages on other subjects on the main Chat index.
"Gloomy? No way, I go to a fab school so I'm rather happy."
Jodie, 11, Lancashire, England
"No way, I don't feel gloomy at all!"
Amy, 9, Buckinghamshire, England
"I didn't feel miserable because I'm in Australia. It's not miserable weather and I'm still in my summer holidays, so I was the opposite!"
Katy, 10, Adelaide, Australia
"Christmas is over and we're back in school (boring). The weather is bad and I feel like rubbish."
Webby, 10, Porthcawl, Wales
"I felt like I feel on any other day. I hate Mondays anyway."
Perry, 10, Luton, England
"I feel really gloomy in the morning because the bad weather gives me a headache."
Ryan, 10, Nottinghamshire, England
"I didn't feel that bad to be honest!"
Ella, 9, Helensburgh, Scotland
"I always find it hard to get out of bed on Monday because the weekend is over and I get maths homework."
Poppy, 10, Leeds, England
"No, I don't feel sad, but a lot of other people do."
Megan, 9, Newcastle, England
"I don't think January is a depressing month because my birthday is on the 8th."
Ellen, 11, Reading, England
"Today has not been depressing for me at all. It's been the best day of my LIFE!"
Robyn, 11, Hove, England
"I do not think that it is really any worse than any other days. Besides, I am always gloomy when it's school."
Miranda, 11, Wales
"I think that you are all bonkers! Today is my birthday and I am quite happy about it. I think that it is the stupidest thing I have ever heard!"
Laura, 10, Hertfordshire, England
"No! I feel extra happy today, it is Martin Luther King day and there is no school!!"
Keri, 13, USA
"That is really weird! I actually do feel quite down today! I feel like this is the beginning of a bad cold."
Layla, 11, Devon, England
"How strange!! I was feeling sad yesterday but I'm happy today, I loved it."
Faatima, 10, England
"I am feeling gloomier today because I got extra homework and the class had to miss break."
Erin, 11, Leeds, England
"No, I am never gloomy on Mondays because you get to see your friends again at school and tell them about the things you did over the weekend!"
Louise, 11, Lancashire, England
"I am so gloomy today because school started. May the big piles of homework begin!"
Marielle, 12, Newport, Wales
"I had an excellent day! I don't know what you're talking about to be honest."
Frank, 13, Somerset, England
"I woke up in a bad mood because the weather was miserable. I was sleepy, had to go to school and I forgot my gym kit!"
Amy, 11, Lanarkshire, Scotland
"I woke up today and did not want to go to school. At school I had my worst lessons."
Sam, 10, Canterbury, England
"I feel really depressed right now... I don't even know why!"
Holly, 15, Wiltshire, England
"I actually am shocked because I do feel depressed today. I also couldn't get up to go to school - I don't normally feel like this."
Chris, 12, Wolverhampton, England
"I'm not sad at all! Because of the weather I got half the day off school and I'm not going back on Tuesday either!"
Claire, 14, Lancashire, England
"I had an ok day today. It was bad when I got told off by my little sister's teacher!"
Lola, 9, London, England
"I woke up this morning and didn't want to get up, but when I got to school it started snowing and I got sent home before we got snowed in. Monday 21st is officially the best day of the year!"
Megan, 15, Northumberland, England
"No, I'm really happy! We've been sent home from school early because of bad weather. I woke up feeling better than normal today!"
Rebecca, 13, England
"I'm very happy today. I don't count it as any other day, just a normal day."
Danielle, 13, Ramsgate, England
"We are very happy today. We are having fun at school because it is snowing and most of the school has been sent home."
Class, 6lb, 10, Newcastle, England
"I really don't turn miserable on any particular day of the week. I'm the one who is always ready first in the morning and am glad to go to school... even though I get really tired!"
Bethany, 10, Hampshire, England
"I am so depressed. I am sick as a dog! But Happy birthday Baby Spice, the tour is wicked, well done."
Kim, 11, London, England
"I woke up very unhappy this morning because I had a bad headache, toothache and a bad tummy. It's only right that I am in a foul mood seeing as I have nothing to be happy about."
Ashleigh, 12, Durham, England
"I am today because I am off school. I feel really ill and bored!"
Lucy, 11, Liverpool, England
"Well I've been diagnosed with depression for a while now, but I must say that actually I'm feeling rather good today."
Tas, 12, Surrey, England
"I am just as happy on a Monday as on every other day. I love Monday!"
Ibsor, 10, Glasgow, Scotland
"I hate Monday mornings!!! I've got to go to school and the Mosque after that. It's well unfair! I wish I had a weekend every day!"
Umayr, 12, Blackburn, England
"I woke up grumpy for no reason. I shouted at my brothers and told my dad that I hate this. I also didn't want to go to school and I lost £20."
Jordan, 9, Bristol, England
"Yes, me and my brother have been grumpier with each other than usual."
Zara, 10, West Sussex, England
"I am a bit sad, but I can always think of something to make me happy."
Maeve, 9, Bray, Ireland
"I'm sad because I've got the infamous stomach bug. My mum let my brother miss a WHOLE WEEK off school but not at all for me! But it's not all sad - today is Emma Bunton's birthday. Happy birthday to her!"
Millie, 13, Wolverhampton, England
"I just suppose that you feel sad because the weekend's over and you have to get up much earlier!"
Ems, 11, Surrey, England
"I am gloomier today because it's dark outside and I don't feel too good."
Gwen, 13, Wales
"I hate every Monday, knowing we have to go back to school. Today I just feel like I can't be bothered."
Lauren, 12, Cheshire, England
"Nope, my day is going excellently! My train was cancelled this morning because of flooding, so I can't go to school at all. I get a free day off to play on the Wii, plus I have a theatre script reading tonight and CAN'T WAIT!"
Madi, 13, Gwynedd, Wales
"I am actually happy!"
John, 7, Leeds, England
"I'm in Australia, the weather is awful, and I think they must be right as I woke up unhappy today."
Em, 14, Australia
"I am not sad as it is my birthday."
Paul, 9, Tiptree, England
"I do feel gloomier than normal because I'm ill, bored and just simply annoyed for no reason."
Hannah, 13, Redhill, England
"I am always happy on Mondays because I hate WEEKENDS!!!!!"
"I think January is the worst month because all the plants are dead and it's always raining."
Jack, 13, Winsford, England
"I woke up felling really gloomy and I do not know the reason."
Rebecca, 8, Paisley, Scotland
"We have tests today."
Jenny, 9, Leicester, England
"When I woke up I felt upset and really grumpy."
"Actually, I seem to feel happier than usual, I wonder why?"
Kez, 10, Ipswich, England
"I don't feel grumpy at all today. In fact I feel very happy!"
Pearl, 12, Carmarthen, Wales
"I am not feeling sad today. Actually, I woke up feeling really excited, and I don't know why!!"
Lauren, 10, Penarth, Wales
"Yes I was gloomier today. I wanted the ground to swallow me up!"
"I think that what the scientists are saying about 21 January being the saddest day is really true. I woke up feeling unhappy and miserable."
Zahrah, 11, Battersea, England
"I am depressed because I have my second to last 11+ today."
Helen, 11, Birmingham, England
"I feel gloomy today... Weekends seem like long holidays and a school week seems like a month!"
Adam, 11, Swansea, Wales
"When I woke up it felt like I had been dropped in a dumpster."
Jake, 9, Sandbach, England
"I'm not depressed today! It's my 13th birthday! Maybe I can be depressed tomorrow because my birthday is over! But not today!"